The research described in this proposal is designed to investigate human information-processing in movement production. We focus especially on speed-accuracy tradeoff relationships that occur in different phases of aimed movements. We will examine the nature of environmental conditions that give rise to such tradeoffs and the types of information processing that underlie them. A primary objective of this research is to develop a more complete, precise model of the movement-control process than now exists. We believe that such a model will give us a better understanding of aimed movements and movement pathologies and deficits in various diseases. The proposed experiments fall into three main series, two of which deal directly with single aimed limb movements and one of which deals with coordinated movements. Our first series concerns the influence of visual information in controlling aimed movements. Our second series concerns the influence of various spatial and temporal constraints and of different payoff matrices on aimed movements. Our third series extends these investigations to movement coordination. As part of these experimental series, and ancillary goal is to develop new empirical procedures and techniques for investigating movement control. Our ultimate aim is to arrive not only at a basic understanding of the speed-accuracy tradeoff and of movement control, but also to find practical applications for our findings.